Post-assembly modification of polymeric composite membranes using spin drying for fuel cell applications

Lee, Kyung Ah,Yoon, Ki Ro,Kwon, Sung Hyun,Lee, Kyung Jin,Jo, Sunhee,Lee, Ju Sung,Lee, Kwan-Young,Lee, Seung Woo,Lee, Seung Geol,Kim, Jin Young The Royal Society of Chemistry 2019 Journal of materials chemistry. A, Materials for e Vol.7 No.13

<P>Self-assembly of inter- and intraphases between the ionomer membrane and mechanical reinforcements in reinforced polymeric composite membranes is of great interest in both physics and chemistry, particularly for proton exchange membrane fuel cell (PEMFC) application. One of the greatest challenges is to obtain an optimally structured polytetrafluoroethylene (PTFE)-reinforced perfluorosulfonic acid (PFSA) composite membrane <I>via</I> solution processing. For high- performance and durable PEMFC applications, the self-assembly of interphases of the ionomers/reinforcements and intraphases of the ionomers in the composite PEM needs to be carefully tailored. Here, we show that post-assembly modification of a PTFE/PFSA composite membrane using a spin-drying method can significantly improve fuel cell performance and reliability. The forced assembly of PFSA ionomers during spinning results in greater infiltration yields into the porous PTFE media. In this way, spin-drying post-treatment results in lower gas crossover and improved mechanical durability. This process also yields larger regions of ionic clusters, which facilitate proton conduction at low relative humidity, affording higher fuel cell currents and greater efficiency.</P>

Original Article : Tenofovir disoproxil fumarate monotherapy for nucleos(t)ide analogue-naive and nucleos(t)ide analogue-experienced chronic hepatitis B patients

( Sang Kyung Jung ),( Kyung Ah Kim ),( So Young Ha ),( Hyun Kyo Lee ),( Young Doo Kim ),( Bu Hyun Lee ),( Woo Hyun Paik ),( Jong Wook Kim ),( Won Ki Bae ),( Nam Hoon Kim ),( June Sung Lee ),( Yoon Jun 대한간학회 2015 Clinical and Molecular Hepatology(대한간학회지) Vol.21 No.1

Background/Aims: This study investigated the antiviral effects of tenofovir disoproxil fumarate (TDF) monotherapy in nucleos(t)ide analogue (NA)-naive and NA-experienced chronic hepatitis B (CHB) patients. Methods: CHB patients treated with TDF monotherapy (300 mg/day) for ≥12 weeks between December 2012 and July 2014 at a single center were retrospectively enrolled. Clinical, biochemical, and virological parameters were assessed every 12 weeks. Results: In total, 136 patients (median age 49 years, 96 males, 94 HBeAg positive, and 51 with liver cirrhosis) were included. Sixty-two patients were nucleos(t)ide (NA)-naive, and 74 patients had prior NA therapy (NA-exp group), and 31 patients in the NA-exp group had lamivudine (LAM)-resistance (LAM-R group). The baseline serum hepatitis B virus (HBV) DNA level was 4.9±2.3 log IU/mL (mean±SD ), and was higher in the NA-naive group than in the NA-exp and LAM-R groups (5.9±2.0 log IU/mL vs 3.9±2.0 log IU/mL vs 4.2±1.7 log IU/mL, P<0.01). The complete virological response (CVR) rate at week 48 in the NA-naive group (71.4%) did not differ significantly from those in the NA-exp (71.3%) and LAM-R (66.1%) groups. In multivariate analysis, baseline serum HBV DNA was the only predictive factor for a CVR at week 48 (hazard ratio, 0.809; 95% confidence interval, 0.729.0.898), while the CVR rate did not differ with the NA experience. Conclusions: TDF monotherapy was effective for CHB treatment irrespective of prior NA treatment or LAM resistance. Baseline serum HBV DNA was the independent predictive factor for a CVR. (Clin Mol Hepatol 2015;21:41-48)

Metastatic thyroid C-cell carcinoma in a beagle dog

Lee, So-Ra,Lee, Mi-Kyoung,Youp, Kyoung-A,Lee, Ah-Ra,Won, Sung-Jun,Kim, Myung-Chul,Kim, So-Yeon,Kim, Yongbaek The Korean Society of Veterinary Science 2013 大韓獸醫學會誌 Vol.53 No.3

An adult beagle dog was presented with a cervical mass detected by palpation and computed tomography. Fine needle aspirates revealed numerous epithelial cells with plasmacytoid appearance and frequent naked nuclei. Histologically, the mass consists of multiple packets of neoplastic cells and extensive areas of necrosis and fibrosis. Neoplastic cells were also found in submandibular lymph nodes. Immunohistochemistry showed that neoplastic cells were positive for calcitonin and negative for thyroglobulin. Based on these findings, the cervical mass was diagnosed as thyroid C-cell carcinoma. Almost one year after the surgical excision, the dog remains healthy without any symptom of recurrence or metastasis.

CASE REPORT : Minute Pulmonary Meningothelial-Like Nodules Simulating Hematogenous Lung Metastasis; A Case Report

( Sang Kook Lee ),( Gi Jeong Kim ),( Young Jae Kim ),( Ah Young Leem ),( Eu Dong Hwang ),( Se Kyu Kim ),( Joon Chang ),( Young Ae Kang ),( Song Yee Kim ) 대한결핵 및 호흡기학회 2013 Tuberculosis and Respiratory Diseases Vol.75 No.2

A 52-year-old man was referred to our clinic for an 11.3 mm nodule in the left lower lobe that was discovered on a chest computed tomography (CT) scan. Eleven small nodules were subsequently found in both lungs. Initially, we performed a transthoracic needle aspiration using CT scan guidance. The pathologic report showed a few clusters of atypical cells that were suspicious for malignancy. The positron emission tomography images revealed multiple lung nodules scattered throughout both lungs. The largest nodule (11.3 mm) in the left lower lobe did not have any discernible fludeoxyglucose uptake. For pathologic confirmation, we consulted a thoracic surgeon to perform the video assisted thoracoscopic surgery. The final diagnosis was minute pulmonary meningothelial-like nodules (MPMNs). MPMNs are benign in nature, and only a few cases require treatment. However, when clinicians are suspicious of potential malignancy, a pathological correlation is essential, even if the final diagnosis is MPMNs.

Minute Pulmonary Meningothelial-Like Nodules Simulating Hematogenous Lung Metastasis: A Case Report

Lee, Sang Kook,Kim, Gi Jeong,Kim, Young Jae,Leem, Ah Young,Hwang, Eu Dong,Kim, Se Kyu,Chang, Joon,Kang, Young Ae,Kim, Song Yee The Korean Academy of Tuberculosis and Respiratory 2013 Tuberculosis and Respiratory Diseases Vol.75 No.2

A 52-year-old man was referred to our clinic for an 11.3 mm nodule in the left lower lobe that was discovered on a chest computed tomography (CT) scan. Eleven small nodules were subsequently found in both lungs. Initially, we performed a transthoracic needle aspiration using CT scan guidance. The pathologic report showed a few clusters of atypical cells that were suspicious for malignancy. The positron emission tomography images revealed multiple lung nodules scattered throughout both lungs. The largest nodule (11.3 mm) in the left lower lobe did not have any discernible fludeoxyglucose uptake. For pathologic confirmation, we consulted a thoracic surgeon to perform the video-assisted thoracoscopic surgery. The final diagnosis was minute pulmonary meningothelial-like nodules (MPMNs). MPMNs are benign in nature, and only a few cases require treatment. However, when clinicians are suspicious of potential malignancy, a pathological correlation is essential, even if the final diagnosis is MPMNs.

Monoculture and Mixture Effects of Green Manure Crops on Soil Quality, Weed Suppression and Organic Red-pepper Production

Lee, Sang-Min,Jung, Jung-Ah,Choi, Bong-Su,Lee, Yong-Hwan,Lee, Jong-Sik,Song, Beom-Heon,Sung, Jwa-Kyung Korean Society of Soil Science and Fertilizer 2011 한국토양비료학회지 Vol.44 No.4

Organic farming is rapidly expanding worldwide. Crop growth in organic systems greatly depends on the functions performed by soil microbes, and nutrient supply weed suppression by green manure crops input. Four red-pepper production systems were compared: 1) bare ground (conventional system); 2) hairy vetch monoculture; 3) rye monoculture; and 4) hairy vetch-rye mixture. Soil inorganic N reached the peak at 30 DAI and hairy vetch monoculture was the highest ($192mg\;kg^{-1}$) and soil total carbon was fluctuated sporadically during the experiment. Carbohydrate and phenolic compounds in soil kept significantly higher in green manure crops systems from 10 DBI to 30 DAI, however the level was the maximum at 10 DBI (carbohydrate) and 30 DAI (phenolic comounds). Incorporation of green manure crops residue enhanced soil microbial biomass C and N throughout the growing season except that MBN in rye was reduced after incorporation. Green manure crops systems suppressed weed occurrence and, in particular, it was prominent in rye monoculture. Mineral elements composition and production in red-pepper fruits were markedly decreased in green manure crops systems although hairy vetch monoculture has come close to bare ground (NPK-applied). Therefore, it was suggested that higher biomass production should be performed not only to improve soil quality and suppress weeds but to yield suitable red-pepper fruits in green manure crops-based organic farming.

Geographic Homogeneity and High Gene Flow of the Pear Psylla, Cacopsylla pyricola Foerster (Homoptera: Psyllidae), Detected by Mitochondrial COI Gene and Nuclear Ribosomal Internal Transcribed Sequence 2

Ah Rang Kang,Jee Yeon Baek,Sang Hyun Lee,Young Sik Cho,Wol Soo Kim,Yeon Soo Han,Iksoo Kim 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.05

The pear psylla, Cacopsylla pyricola Foerster (Homoptera: Psyllidae), is a serious insect pest of commercial pear crops. The species, which resides on pear trees throughout its life cycle, is rapidly spreading in some regions of the world. Given the life cycle, it is unclear how such a rapid spread has been facilitated. Presently, the population genetic structure of the species including genetic diversity and gene flow was studied to understand the nature of dispersal and field ecology of the species. Pear psylla was collected from several pear orchards in Korea. The 658-bp region of mitochondrial COI gene and the 716-bp long complete internal transcribed spacer 2 (ITS2) of the nuclear ribosomal DNA were sequenced. Unlikely other previously studied insect pests, the COI-based genetic diversity of the pear psylla was extremely low (maximum sequence divergence of 0.15%). This finding allowed us to conclude that the species may have been introduced in Korea relatively recently, possibly with the phenomenon of genetic bottlenecks. ITS2 sequence-based analyses of phylogeny, population differentiation, gene flow, and hierarchical population structure all concordantly suggested that the pear psylla populations in Korea are neither genetically isolated nor hampered for gene flow. These genetic data are concordant with the dispersal of an overwintering winterform morph outside the non-pear habitat in the fall and the possibility of subsequently longer distant dispersal.

A Comparison of Differential LC VCOs with Enhanced Tank Structure and Filtering Techniques in InGaP/GaAs HBT Technology

Sang-Yul Lee,Jae-Ho Yoon,Ah-Rah Koh,Bhanu Shrestha,Sang-Hoon Cheon,Nam-Young Kim 한국통신학회 2006 한국통신학회 학술대회논문집 Vol.2006 No.7

Electrospun smart fabrics that display pH-responsive tunable wettability

Lee, Chang Hwan,Kang, Sung Kyung,Lim, Jung Ah,Lim, Ho Sun,Cho, Jeong Ho The Royal Society of Chemistry 2012 Soft matter Vol.8 No.40

<P>Smart fabrics that reversibly switch between superhydrophobicity and superhydrophilicity were developed using a combination of hierarchical nanostructured fibrous webs and a pH-responsive polymer that experiences pH-dependent conformational transitions, poly[2-(diisopropylamino)ethylmethacrylate-<I>co</I>-3-(trimethoxysilyl)propylmethacrylate].</P> <P>Graphic Abstract</P><P>Smart fabrics that reversibly switch between superhydrophobicity and superhydrophilicity were developed using a combination of hierarchical nanostructured fibrous webs and a pH-responsive polymer that experiences pH-dependent conformational transitions, poly[2-(diisopropylamino)ethylmethacrylate-<I>co</I>-3-(trimethoxysilyl)propylmethacrylate]. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2sm26625c'> </P>

Obturation efficiency of non-standardized gutta-percha cone in curved root canals prepared with 0.06 taper nickel-titanium instruments

Lee, Eun-Ah,Kim, Sung-Kyo 大韓齒科保存學會 2005 Restorative Dentistry & Endodontics Vol.30 No.2

The purpose of this study was to evaluate the obturation efficiency of a non-standardized gutta-percha cone in curved root canals prepared with 0.06 taper nickel-titanium instruments. Sixty simulated curved root canals in clear resin blocks were prepared with crown-down technique using 0.06 taper rotary ProTaper and ProFile (Dentsply-Maillefer) until apical canal was size 30. Root canals were randomly divided into 4 groups of 15 blocks and obturated with cold-laterally compacted gutta-percha technique by using either a non-standardized size medium gutta-percha cone or an ISO-standardized size 30 one as a master cone. Gutta-percha area ratio were calculated at apical levels of 1, 3 and 5 mm using AutoCAD 2000 after cross-sectioning, and the data were analyzed with one-way and two-way ANOVAs and Duncan's multiple range test. Non-standardized size medium cone groups showed significantly higher gutta-percha area ratio than standardized cone groups at all apical levels (p < 0.01). Non-standardized cone groups used significantly less accessory cones than standardized cone groups (p < 0.01). 최근, 다양한 경사도의 니켈-티타늄 근관기구와 더불어 다양한 경사도의 gutta-percha cone이 소개되었다. 효율적인 근관 충전을 위해서는 짧은 시간에 적은 수의 기구 및 재료를 사용하여 균일한 gutta-percha로 근관을 충전할 필요가 있다. 본 연구에서는 0.06 경사도의 니켈-티타늄 전동화일로 형성된 만곡 근관에서 측방 가압법으로 근관충전시 비표준화 medium 크기 master gutta-percha cone의 충전효율을 ISO 표준화 규격의 master cone과 비교하여 평가하고자 하였다. 60개의 모형레진 만곡근관에서 0.06 경사도의 니켈-티타늄 전동화일 (ProTaper, ProFile, Dentsply-Maillefer, Ballaigues, Switzerland)을 사용하여 근단부 근관이 30번 크기가 되게 crown-down법으로 근관을 형성하였다. 근관은 master gutta-percha cone, AH 26 실러 (Dentsply-DeTrey, Konstanz, Germany), 그리고 type A accessory cone (Dentsply-Maillefer, Ballaigues, Switzerland)을 사용하여 측방가압법으로 충전하였으며, 이 때 사용된 master gutta-percha cone(Diadent, Chongju, Korea)과 Finger spreader(B type, Dentsply-Maillefer, Ballaigues, Switzerland)에 따라 임의로 15개씩 4개의 군으로 나누어 실험하였는데, St/SS 군에서는 ISO 표준화 규격의 30번 master cone과 스테인레스 스틸 finger spreader를, St/NT 군에서는 ISO 표준화 규격의 30번 master cone과 니켈-티타늄 finger spreader를, Non-St/SS 군에서는 비표준화 medium 규격 master cone과 스테인레스 스틸 spreader를, 그리고 Non-St/NT 군에서는 비표준화 medium 크기 master cone과 니켈-티타늄 finger spreader를 각각 사용하였다. 충전된 근관은 37℃, 상대습도 100%하에서 24시간 보관한 후, 치근단 1, 3및 5 mm수준에서 횡절단하여 입체현미경 하에서 관찰하고 컴퓨터에 저장한 다음, AutoCAD 2000 프로그램을 이용하여, 형성된 근관 및 gutta-percha 충전물의 외형을 추적하여 근관내 gutta-percha 면적비를 계산하였다. Gutta-percha 면적비의 결과치는 two-way ANOVA를, 그리고 accessory cone 수는 one-way ANOVA 및 Duncan's multiple range test를 이용하여 통계 분석하여 다음과 같은 결과를 얻었다. 스테인레스 스틸 finger spreader를 사용한 경우 및 니켈-티타늄 finger spreader를 사용한 경우 공히, 모든 치근단 수준에서 비표준화 medium 크기 master cone 사용군이 ISO 표준화 규격의 master cone 사용군에 비해 유의하게 높은 gutta-percha 면적비를 나타내었다 (p < 0.01). 비표준화 medium크기 master cone 사용군에서는 표준화 규격의 master cone 사용군에 비해 유의하게 적은 수의 accessory cone이 사용되었다 (p < 0.01).